Re: OSPF TLVs

["Naidu, Venkata" <[e-mail]>]

Kireeti,

  Good that you are listening to this :-)

-> > You appear to be precluding TLVs from having any length
-> that is not a
-> > multiple of four bytes. This seems unnecessary.
->
-> (I don't think Venkata says that.  But then again, he can chime in.)
->
-> > What we currently have is a rule that tells you how to
-> encode a TLV into an
-> > OSPF LSA if it is not a multiple of four bytes.
-> > You have a separate rule that says that a specific TLV has
-> some reserved
-> > bytes.
->
-> If a TLV has reserved bits/bytes that it explicitly defines, that's
-> just part of the Value field as far as the TLV is concerned.
->
-> > Why do we need to make any changes?
->
-> Why indeed?  :-)

  Let me try one more time. I didn't ask for any change(s).
  I am giving the below modified RFC 3630 figure to better understand
  the issue at hand.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Type             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Value Current...                         |
   .                                                               .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .                      Value Reserved...                        .
   .                                                               .
   .               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .               |                   Pad ... (0-3 octet)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  Adrain said: if there is "reserved space" inside the Value
  field, that must be included in the Length field.

  I said: In such an interal "reserved space" case, there must
  be some way to know the boundary to parse and seperate the
  "Current value" field and "Reserved value" field. If the Length
  field signifies both "Currnet + Reserved" values then the only
  way to know the boundary is by Type field.

  Both of us agreed on:

  1. Renaming "internal value padding" to "Reserved Value"

  2. Four octet boundary padding length (0-3 octets) will NOT
     be included in the Length field.

  Now please tell me, am I clear this time ? :)
  If I am wrong, where am I ?

-> > The only change that might be of use would be to change
-> the name of any
-> > field that is included in a TLV from "padding" to
-> "reserved" to avoid
-> > confusion.
->
-> Good idea.

  Agree.

Venkata.